The subject matter disclosed herein relates to aircraft. More specifically, the subject disclosure relates to inlet ducts for aircraft engines. Engines in some aircraft, for example, helicopters, are positioned such that there is an inlet duct opening at each lateral side of the airframe. Inlet airflow to the engine enters the inlet duct openings and travels down a bifurcated, or split, inlet duct before reaching the engine inlet. Such a configuration often results in significant pressure and flow distortion at yaw angles of the aircraft. Ram pressure effects on the inlet duct side facing freestream air increases the pressure in that leg of the bifurcated duct, while the pressure in the leg of the bifurcated duct in the “flow shadow”, or partially obscured by the airframe, is significantly less, resulting in engine inlet distortion adversely affecting engine performance.
Further, some aircraft require reverse flight operations which also results in significant engine inlet pressure and flow distortion when utilizing the typical bifurcated inlet duct.